/Engine/Source/Editor/SkeletonEditor/Public/IEditableSkeleton.h
Function to tell you if a socket name already exists. SocketParentType determines where we will look to see if the socket exists, i.e. mesh or skeleton
bool DoesSocketAlreadyExist ( const class [USkeletalMeshSocket](API\Runtime\Engine\Engine\USkeletalMeshSocket) * InSocket, const [FText](API\Runtime\Core\Internationalization\FText) & InSocketName, ESocketParentType SocketParentType, [USkeletalMesh](API\Runtime\Engine\Engine\USkeletalMesh) * InSkeletalMesh ) const